This invention relates to thermal fiber drawing and more particularly to a thermal fiber drawing process adapted to synthesize a chemical compound in situ that has a melting temperature exceeding the draw temperature.
Thermal fiber drawing is a process in which a macrostructured preform is heated and drawn into extended lengths of microstructured fiber. New methods of increasing both the structural complexity of fibers and number of materials compatible with the drawing process are substantially expanding the functionality of photonic crystal and semiconductor device fibers (1-3). The numbers in parentheses refer to the references listed herein. The contents of all of these references are incorporated herein by reference. The drawing process, however, has always been limited to materials that flow at the draw temperature. Many have tried to avoid this limitation by depositing desired materials inside (4-7) or onto the surface (8-11) of a previously drawn fiber. These post-drawing processes, do not take advantage of the scaling associated with fiber drawing, are limited in their architectural complexity and the length over which uniform structures can be produced.
It is thus an object of the present invention to overcome the requirement that the constituent materials be fluid (high or low viscosity) at the drawing temperature.